This invention relates generally to telemetry receivers for use with implantable devices such as heart pacemakers and, more particularly, to telemetry receivers adapted to process data received from such devices in any of a number of possible modulation formats.
Implantable devices such as heart pacemakers ordinarily accumulate data indicating the condition of various of the pacemaker's internal parameters, as well as a log of pacing activity and of the heart's condition. Periodically, this accumulated data is transmitted via telemetry to an external device, called a programmer. The transmitted data is modulated according to any of a number of conventional modulation schemes, including amplitude modulation, frequency modulation and phase modulation. The transmitted data also is received in any of a number of conventional data rates and frequencies.
Typical programmers have in the past included various bandpass filters and demodulators for demodulating and detecting the telemetered data signal. Appropriate switches are provided for directing the received data signal to the appropriate hardware circuits according to the signal's known format.
Data signals commonly are telemetered by the implantable device in either of two conventional modes, including a reflected-impedance mode and an active mode. In the reflected-impedance mode, the implantable device merely opens and closes a switch connected across a coil, in accordance with the data to be transmitted. Internal power is not utilized to generate electromagnetic radiation; instead, the device provides a variable load on electromagnetic radiation transmitted by the programmer, which is detected by the programmer. In the active telemetry mode, on the other hand, the implantable device utilizes internal electrical power to transmit the data outwardly via an antenna. Many programmers include front-end receiver hardware adapted to receive data telemetered via both the reflected-impedance mode and the active mode.
The programmers described briefly above have proven to be effective in receiving data telemetered from implantable devices and modulated according to any of a number of conventional schemes and data rates. Although such programmers have performed generally effectively, they are considered to be unduly complex and bulky. There is a need for a programmer apparatus of this kind that is configurable to receive and demodulate data telemetered from a variety of implantable devices according to many different modulation schemes, with reduced complexity and size. The present invention fulfills this need.